The present invention relates to an intermediate chain bucket conveyor.
Conveyors of the above mentioned general type are known in the art. One such conveyor is disclosed, for example, in the German patent No. 2,038,616. This conveyor has a U-shaped forward conveyor part at the side of a sole and open toward the roof, and a return conveyor part at the side of backfilling and closed in a substantially channel-like manner, wherein the return conveyor part is normal to the forward conveyor part. An endless chain including a bucket chain member and a plurality of buckets mounted thereon move in the above mentioned conveyor parts. This conveyor has the advantage, as compared with the bucket conveyor with superimposed conveyor parts, that in the event of cessation of the return conveyor part located under the forward conveyor part, chain cracks no longer can take place which are particularly produced by small coal. It is thereby no longer necessary to lift the conveyor for elimination of these chain cracks. Furthermore, in such a conveyor no failures take place because of flamming under the conveyor, and contacts between the chain portion moving in the return conveyor part and the sole as a result of movement of the conveyor in the longitudinal direction of the transverse passage. A very important advantage of this conveyor is the fact that the energy dissipation by the return conveyor part at the sole side is reduced from approximately 50% to a considerable value. Moreover, since the forward conveyor part is arranged directly on the sole, the conveyor has a very small height, whereby the material removed from the mine face can be loaded onto the conveyor with considerably smaller expenditures. Finally, the vertically arranged and thereby easily accessible return conveyor part at the backfilling side forms a natural shield for driving and no additional means is necessary.
Despite the above described advantages, this conveyor has not been implemented in practice, inasmuch as it was not possible to solve the problems in the region of the drive and reverse stations for transporting the chain from one to the other conveyor part. These difficulties result from the fact that, at one end of the conveyor line, the chain with the central conveyor chain member must run, in the event of substantially vertical buckets, from the forward conveyor part in a substantially horizontal position into the forward conveyor part, and at the other end must again run from the horizontal position into the vertical position. Thereby, spatial turning of the buckets by 90.degree. is required. Suitable drive and/or reverse stations which would be capable of spatial movement of the buckets of the chain have not been available.
In a bucket conveyor with two outer chains, a forward conveyor part located at the side of a sole, and a return conveyor part arranged normal thereto which is disclosed for example in the German patent No. 679,604 reversing of the chain is performed. This reversing is carried out with the aid of a complicated spatially curved chain channel which is provided at the junction on the chain wheel is conventionally rotatable about a horizontal axis. Since in this case both outer chains must cover paths of considerably different lengths, this necessarily leads to clamping and thereby disturbances of the mining operation. Furthermore, considerable wear cannot be avoided. Also, the construction expenditures are high, since the chain channel must be stabilized with the consideration of the not insignificant chain pulling forces.
A further problem with chain wheels rotatable about horizontal axes is that it is desirable to retain the outer diameter as small as possible in view of the entire height of a machine frame. This leads, as a rule, to the fact that the bucket chains travel from one to the other conveyor parts with a relatively great curvature. As a result of this, only a small number of chain links and particularly only horizontal chain links come into engagement with the respective buckets in the chain wheel. The great radius of curvature acts also in such a manner that the superimposed chain links are considerably inclined relative to one another, whereby they are subjected to high wear. This is further aggravated by the fact that only each second particularly horizontal chain link is embraced by the chain wheel in interengaging and force-transmitting manner and transmits the force in the bucket chain.
A so-called wing bucket conveyor with only one outer chain is disclosed in German patent No. 809,415. It employs a roller chain which runs over the respective guides always at an angle of 45.degree. to the sole. Thereby a simple chain wheel for reversing the bucket chain is sufficient, whose axis of rotation with regard to its inclination must correspond to the inclined rotary position of the bucket chain. The bucket wings are pivotally connected by a folding mechanism with the bucket chain so that they can fold into the return conveyor part against the running direction downwardly.